(1) Field of the Invention
The present invention relates to a memory system which includes a memory device having a nonvolatile memory, and an access device for accessing the memory device.
(2) Description of the Related Art
A memory system (nonvolatile memory system), which includes a removable memory device having a nonvolatile memory, and an access device for accessing the memory device, is known for an example in Japanese Laid-Open Patent No. 2001-142774. The configuration of the memory system is shown in FIG. 1.
A memory card 500, which has a rewritable FLASH Electrical Erasable Programmable Read Only Memory (EEPROM) 501, contains a controller 502. The controller 502 converts a logical address, which has been sent from a host device 550 for accessing FLASH EEPROM, into a physical address. The physical address is used for writing/reading data to/from the FLASH EEPROM 501. Address management information for converting the logical address is retained in a management area in the FLASH EEPROM 501, and then a necessary part of the address management information to access a requested address is read out and sent to a Static Random Access Memory (SRAM) 506.
According to the memory card 500 of the aforesaid conventional configuration, the following processing is necessary: the address management information is sent from the FLASH EEPROM 501 to the SRAM 506 at the start of an operation; and then the updated address management information is sent from the SRAM 506 to the FLASH EEPROM 501 at the end of the operation.
As an alternative to the aforesaid conventional configuration, it has been suggested in Japanese Laid-Open Patent No. H07-219720 that the address management information is retained in a nonvolatile RAM instead of the volatile SRAM 506. The configuration of the memory system is shown in FIG. 2. A ferroelectric memory and the like are used for a nonvolatile RAM 606.
This exemplified configuration shown in FIG. 2 enables to skip steps for sending address management information at the start and the end of the operation, so that the processing time at the time of inserting/removing a memory card 600 into/from the host device 550 can be reduced.